In a field of image processing, there is a case where one might want to determine whether an image includes a character area inserted by an image editing, or specify (detect) all character areas inserted by the image editing in the image.
For example, in a case of a virtual mall site, one might want to extract an item image (a product image) that does not have text such as “free shipping”, “Grand Prize Winner” or the like from item images of shops in the virtual mall, and use the item image on a top page or the like. In this case, it is necessary to determine whether the item image includes the character area inserted by the image editing.
Further, in the virtual mall site, one might want to check whether text that is illegal under the Pharmaceutical Affairs Law or the like, for example, is written on an item image. In this case, it is necessary to specify every character area inserted by the image editing from the image.
As a technology to specify a character area included in an image, the technology disclosed in Patent Literature 1 is known, for example. Patent Literature 1 discloses technology for specifying a character area of advertisement leaflets in which characters and images are laid out (see paragraphs 0019 and 0020, and FIG. 3). In the technology disclosed in Patent Literature 1, image data is separated for each color, and a plurality of pieces of color image data is thereby generated. Further, an edge part is specified using the variable density of image data, and an area that only includes amount of edges less than a predetermined value is specified as a photograph area. A character area is then specified for each piece of color image data based on the photograph area.